Performance Issues on ccNuma-System

[Christoph Statz]

Hello Matt,


>
> That stuff is rarely worth running. Without a decent model of the
> performance, the
> data is no help. I am not talking about network bandwidth, but  
> memory bandwidth.
> For a sparse matvec that comes from a simple scalar PDE, you need  
> incredible
> amounts of bandwidth to drive the tiny amount of flops. The equation
> is in the paper.
>
>> Please see the paper
>>   by Kaushik and Gropp which models sparse matvec performance (on
>> Dinesh's website).
>>
>> Which Paper on which website. Please send a link.
>
> I believe you want 11 and 17 here http://www.mcs.anl.gov/~kaushik/
> under the Publications link.

Got it. I will look at it and check the memory bandwidth

>
>
>> 3) You would see better performance using a block method. Sparse  
>> matvec
>> without
>>   blocks will never see good percentages of peak (ditto for  
>> backsolve).
>>
>> How do I use the block methods?
>> Since I rely on the "user-level" interfaces kspsolve etcpp., I  
>> don't see how
>> i could influence this.
>
> You can't unless your system has block structure. If it does, you can
> use the BAIJ
> matrix types.

I'll try it.
Thank you for your advice that far.

Sincerly,
Christoph



>
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